Hydraulic valve sleeve



y 1960 H. H. LAUCKS 2,938,503

HYDRAULIC VALVE SLEEVE Filed Feb. 15, 1950 IN VEN TOR.

HOWARD H LAUCWS BYW LQQWSEQQK 1977" ORA/E Y HYDRAULIC VALVE SLEEVEHoward H. Laucks, Boonton, N.J., assignor to Bendix AviationCorporation, Teterboro, N.J., a corporation of Delaware Filed Feb. 15,1950, Ser. No. 144,303

4 Claims. (Cl. 12146.5)

The present invention relates to hydraulic valves-and more particularlyto that type used in hydraulic servo systems.

Heretofore, valves of this nature have had the disadvantage that atleast six critical machining dimensions were required in the manufacturethereof, since the distance between the inlet and outlet ports on themoving part, and the distance of these ports from their respective endsof said part had to be held to very close tolerances, and saiddimensions, in addition, had to match very closely the matchingdimensions on the stationary part.

While means for adjustment of the moving part with respect to the portson the stationary part have been devised, these have seldom beeneffective on. those types of valves that are too small to be internallyadjustable.

It is therefore, one of the objects of the present invention to providea hydraulic valve for a servo system wherein the foregoing disadvantagesare eliminated, and to do so in a novel and effective manner.

Another object of the present invention is to provide a servo valvedesigned in two pieces to reduce the number of critical machiningdimensions.

Still another object of the invention is to provide adjustment meanswithin a servo valve which will be effective on valves that are toosmall to be internally adjustable.

Still another object of the invention is to provide a hydraulic valvefor a servo system which shall be simple and economical to manufacture,durable and reliable in operation, and yet positive and effective inperformance.

The foregoing and other objects and advantages will appear more fullyhereinafter from a consideration of the detailed description whichfollows, taken together with the accompanying drawing wherein oneembodiment of the invention is illustrated by way of example. It is tobe expressly understood, however, that the drawing is for the purposesof illustration only and is not to be construed as defining the limitsof the invention.

The drawing is a view partly in section of a hydraulic mechanismembodying the device.

Referring now to the drawing wherein like reference characters designatelike parts, a hydraulic servo mechanism 10 includes a casing 12including valves 14 and 16 and a torque motor 18 and a servo motor 18ahaving a power piston 18b. The torque motor 18 may be of a type wellknown in the art wherein the motor shaft, not shown here, is adapted torevolve selectively in either direction. Dual arms 20 and 21 are mountedon the motor armature for reasons hereinafter explained.

A pair of inlet pressure ports 22 and 24 connect to passageways 26 and28 respectively, in the casing 12 which lead to inlet ports 30 and 32 insliding valve sleeves 34 and 36. A pair of bores 38 and 40 in the casing12 house the valve sleeves 34 and 36 which in turn accommodate themoving valve elements 42 and 44 which in turn control the valve ports 46and 48, respectively, in the sleeves 34 and 36. I

A pair of fluid passages 50 and 52 connect the drain Patented May 31,1960 ports 54, 56 and 58 and 60 of the sleeves 34 and 36 to a commonfluid pressure drain outlet 61. To provide means whereby the port 46 maybe placed in communication with either the inlet port 30 or the drainport 54, the valve member 44 is provided with a land 78 that is adaptedto control the port 46.v The land 78 is constructed so as to have theouter dimensions thereof closely match the port 46 and a centrallydisposed annular groove 77 may be formed in the land 78 in order toreduce the weight of the valve member 44. The valve member 44 is furtherprovided with annular grooves 79 and 81 that are axially disposed to theright and left respectively, of the land 78. The grooves 79 and 81 neednot be accurately machined since they serve merely as conduits orpassageways between the inlet 30 and the port 46 and the drain 54 andport 46, respectively. Thus, the only element of the valve member 44requiring accurate axial dimensioning is the land 78 and therefore, theconstruction or manufacture of the valve member 44 is greatlysimplified. Lands 85 and 87 formed at the opposed extremities of thevalve member 44 and a land 89 formed intermediate the lands 78 and 85serve principally to guide the valve member 44 during its reciprocationand to prevent axial leakage of fluid along the member 42.

Due to the foregoing construction upon a movement of the valve member tothe left the port 30 is placed in communication with the port 46 throughannular groove 79 While a movement of the valve member 44 to the rightconnects the port 46 to the drain port 54 through annular groove 81.

The fluid entering inlet 30 is under a relatively high pressure andtherefore axial leakage along the valve 44 past the land 89 may occur.Such leakage, however, is accommodated by the drain port 56 whichdirects the fluid through passageway 50 to the drain 61. On the otherhand, the fluid flowing between port 46 and drain port 54 is under arelatively low pressure and hence axial leakage past the land 87 isslight and is taken care of by drain port 83 which communicates to theatmosphere at exterior of the casing 12. The drain port 83 also preventsthe hydraulic locking of the valve member 44.

To control communication between the port 48 and either inlet port 32 ordrain port 60, the valve member 42 is designed and constructed similarto the valve member 44. Thus, a land 76 having a centrally disposedannular groove 91 is dimensioned to closely match the port 48. Annulargrooves 93 and 95 axially disposed on left and right sides respectively,of the land 76 afford means whereby either the inlet port 32 or drainport 60 is placed in communication with the port 48 upon the axial dis.-placement of the valve member 42. Thus, when the valve member 42 ismoved to the left, the inlet port 32yis connected to the port 48 andwhen the valve member 42 is moved to the right, then the port 48 isconnected to the drain 60. I

The valve member 42 is provided at the opposed ends thereof with lands97 and 99 and with a land 101 that is formed between the lands 76 and97. Axial leakage past land 101 is returned to drain 61 through port 58and passageway 50 while axia1 leakage past land 99 is past to theexterior of the casing through drain ports 83a. The drain ports 83a alsoserve to inhibit hydraulic locking of the valve member 42. a The valveports 46 and 48 lead through passageways 46a and 48a to the power piston18b of the servomotor 18a. For example, the valves 14 and 16 areoperated in opposite directions so that when the position of the land 78of valve member 44 connects the ports 46, and 30, then the position ofthe land 76 on valve member 42 will be connecting ports 48 and 60 thushigh pressure fluid will flow to the power piston 18b at port 46 anddrain fluid will be returned from the power piston 18b atpo'rt 48. Themotor 18 responsive to the requirements of the hydraulic system isadapted to provide motion to valves 42 and 44 so that either port 46 or48 may be connected to high pressure fluid while the remaining port 46or 48 will thereby be connected to drain. The valve 14 governs theapplication of fluid pressure to and fluid exhaust from one side of theservo piston 18b while the valve 16 governs the application of fluidpressure to or fluid exhaust from the opposite side of the power piston18b. The valves 14 and 16 are arranged for operation by the motor sothat upon movement of the motor 118 in the direction from the nullposition the valve 14 will connect one side of the servo piston 18b tothe source of fluid pressure, while the valve 16 will connect theopposite side to fluid exhaust. Movement of the motor 18 in the oppositedirection from the null position will have the opposite effect.

There is further provided means for independent adjustment of the valveelements 42 and 44 as follows: A flexible wire 62 is secured to the dualarms 20 and 21, as at 64 and 66, and to the valve elements-42 and 44, asat 68. The sliding sleeve elements 34 and 36 are held against a hollowexternally'threaded adjusting screw 70 by means of a relatively stiffspring 72 positioned against the opposite end of the sleeves 34 and 36and anchored against the casing 12. A thin walled close fitting tube 74may encase the wire 62 for reinforcement purposes.

arms 21 and respectively, does not require extreme accuracy since thesleeves 34 and 36 and therefore, the ports 46 and 48 may be adjustedrelative to the lands 78 and 76 to make up for any error in the mountingof the valve members 44 and 46. Thus it is possible to accomplish thesetting and adjustment of valves that are relatively small and otherwisecould not be adjusted inter nally.

Although only one embodiment and one application of the invention hasbeen illustrated and described, other changes and modifications in theform and relative arrangement of parts, which will be apparent to thoseskilled in the art, may be made without departingfrom the spirit andscope of the invention.

What is claimed. is:

l. In a hydraulic servo valve operated by a torque motor, a casing, apair of bores in said casing, a slideable valve sleeve within each ofsaid bores, adjustable As hereinbefore described, the drain ports 83 and83a communicate with the atmosphere and therefore the ends of the valvemembers 44 and 42 adjacent these ports are exposed to the atmosphere atthe exterior of the casing 12. Due to the hollow screws 70, the oppositeend of the valves 44 and 42 are also exposed to atmosphere, and thus,the opposed ends of the valve members 44 and 42 are exposed toprevailing atmospheric pressure.

Having thus described the invention, it will now be apparent to thoseskilled in the art that when fluid under pressure is applied to theinlet ports 22 and 24, it will pass along passageways 26 and 28 throughthe inlet ports 30 and 32. Thereupon, dependent upon the position of thevalve elements 42 and 44 containing the lands 76 and 78, high pressurefluid will pass through either port 46 threaded means in one end of eachof said bores, spring means biasing said sleeves against said threadedmeans, a movable valve element within each sleeve, 21 wire attached toeach movable element and extending through said threaded means, saidwires diametrically attached to said motor, a pair of pressure inletports in said casing leading to said valves, ports in said sleeves forsaid inlets, a control port in each sleeve, a drain port in each sleeveat opposite sides of said inlet and control ports, a land on eachmovable element for governing fluid conditions at said control ports,said lands being positioned by said motor.

2. In a hydraulic servo valve, a casing including a through bore, anadjustable sleeve within said bore, spring means biased against one endof said sleeve, a hollow or 48 and passageways 46a or 48a to drive thepower 1 piston 18b and the fluid on the opposite end of the power piston18b will be returned through the remaining port (46 or 48) which isconnected to drain port 54 or 60.

Since the opposed ends of the valve members 44 and 42 are exposed toatmospheric pressure, it is apparent that the prevailing atmosphericpressure does not eflect the I operation of the device. The valves 14and 16 in the illustrated embodiment are shown in null position. Thetorque motor 18 which is responsive to the requirements of the hydraulicservo system governs the positioning of the valve elements 42 and 44 bymeans of wires 62 attached to the dual arms 20 and 21 which are attachedto the motor shaft.

The independent adjustment of the valves 14 and 16 to a line andsensitive degree is readily accomplished by turning the screws 71},thereby axially adjusting the moving sleeves 34 and 36 and hence theports 46 and 48 thereof with respect to the lands 76 and 78. The rigidsprings 72 hearing firmly against the sleeves 34 and 36 obviate thepossibility that the sleeves will slide from their set position. Sincein the manufacture of the sleeves 34 and 36 and the valve members 44 and46 the only accurate axial dimensioning required is of the ports 46 and48 in the sleeves 34 and 36 and the lands 78 and 76 in the valve members44 and 46, it is apparent that a threaded member engaging the other endof said sleeve for adjusting said sleeve against said spring means, saidhollow threaded member communicating one end of said bore to atmosphere,a pressureinlet and a control port in said sleeve, drain port means insaid sleeve, drain port means in said casing communicating the other endof said bore to atmosphere, armovable valve ele-v the combinationcomprising a casing including a pair of bores, a fluid pressure port anda fluid outlet for each here, an adjustable sleeve in each bore, springmeans biased against each sleeve, threaded means for independentlyadjusting'each sleeve against said spring means, mating ports for saidfluid pressure and outlet in each of said sleeves, a control port insaid sleeves, a movable valve element within each sleeve, wire meansattaching each of said elementsto said motor, a land on each elementcooperating with said fluid pressure and outlet ports and said controlports, said motor slideably operating-said elements in an opposite senseto control the fluid flow at said control ports.

4. For use in a hydraulic servo system where the flow 'of fluid suppliedto a power piston is controlled by a 'for independently adjusting eachsleeve against said spring means, mating ports for said fluid pressureand outlet in each of said sleeves, a control port in said sleeves, amovable valve element within each sleeve,

wire means attaching each of said elements to said motor, a land on eachelement cooperating with said fluid pressure and outlet ports and saidcontrol ports, said motor slideably operating said elements in anopposite sense to control the fluid flow at said control ports, saidcasing having a port opening one end of the bore to atmosphericpressure, and said hollow threaded means opening the opposite end ofthis bore to atmospheric pressure so as to apply prevailing atmosphericpressure to opposite ends of the valve element and sleeve.

References Cited in the file of this patent UNITED STATES PATENTS AikenDec. 15, 1891 Lower Mar. 13, 1917 Proell Sept. 8, 1931 Spellman Oct. 29,1935 Frentzel May 26, 1942 Donaldson Dec. 15, 1942 Giger Oct. 30, 1945Yates Dec. 10, 1946

